As a general manufacturing method of phosphor film for use in a color cathode ray tube, there are a slurry spread method using a phosphor slurry, and a powder spraying method using phosphor powder. The above described powder spraying method which has been recently developed is classed as a dry dusting method and a wet dusting method, which are disclosed in U.S. Pat. Application Ser. No. 07/238401 filed by this applicant now U.S. Pat. No. 5,002,844. These two types of dusting methods, as explained in detail in the above application, are characterized in that they indirectly form phosphor film by using photoresist layer and phosphor powder, unlike the slurry spread method. Being different from the conventional slurry spread method which can obtain the phosphor stripe having the width about within 30 to 40 .mu.m, these powder spraying methods can obtain smaller width than 10 .mu.m, so that they are very proper for manufacturing a finer phosphor screen. Thus, the above wet dusting method which is generalized as a manufacturing process of phosphor surface of cathode ray tube for industrial use such as a monitor for a computer has merits in having phosphor strip which is finer and has higher color purity than that of the dry process.
Hereinafter, the dry dusting method and the wet dusting method as the powder spraying method will be briefly explained to help the understanding of the present invention which will be explained later.